Limited landfill capacity and an increase in the environmental awareness and government regulations have spurred efforts for the recycling of post-consumer and post-industrial, synthetic and natural polymeric material. About 2 billion pounds of carpet is produced annually in the United States that starts showing up as waste after about seven years, and together with some 40 million pounds of waste carpet ends produced per year in the manufacture of carpets constitute a very serious environmental issue. It is this same limited landfill capacity that have also motivated efforts involving recycling of post-consumer and post-industrial synthetic and natural polymeric material. In the making of garments, about 15% of the fabric is waste. When the waste fabrics are blends, primarily polyester fibers and cotton fibers, this waste fabric (estimated to be about one billion pounds), is generally landfilled and constitutes a very serious environmental issue.
Typical conventional carpeting includes three primary components: (1) a face yarn that generally consists of nylon-6 or nylon-6,6 fibers with smaller amounts of polyester, polypropylene, acrylics, wool and cotton fibers; (2) a carpet backing that is generally made of polypropylene fibers with a much smaller amount of jute fibers; and (3) an adhesive material that is usually styrene-butadiene rubber and is applied as a latex and cured after application. The adhesive is usually filled with a very high melting inorganic material such as calcium carbonate. These typical carpet constructions are well known in the art and are exemplified in U.S. Pat. No. 4,643,930. Because of the diverse chemical structure of the melt incompatible fiber components of waste carpet, recycling of this material presents a particularly difficult technological challenge.
Previous efforts for disposing waste carpet materials by individuals and corporations have relied on burning the waste carpet in massive incinerators, separating the face yarn followed by depolymerization to recover the monomers of the polyamides or polyester material, or use of the face yarn in special products, using supercritical fluids to dissolve the face yarn, and melt extruding the unseparated carpet components into a polyblend composite, which is described in U.S. Pat. No. 5,294,384. The above processes have not been satisfactory from either environmental or economic factors, while the melt extruded polyblend has particularly weak interfacial adhesion between the incompatible blend components and does not produce a very satisfactory product.
Waste fabrics constitute another large source of waste fibers, however they are often composed of blended yarns and fibers. These fibers consist of the natural type, the major ones being cotton, wool and silk and the synthetic type, the major ones being polyester, nylons, acrylic and polyolefins. These fabrics are almost always dyed in a variety of colors and may contain a variety of surface additives. Because of the variable colors and fiber composition, little use can be found for these waste materials. However, this waste is produced at a very limited number of manufacturing sites, making collection a simpler task compared to the collecting from the general public. This material is also clean and can be readily shipped to central processing centers without special handling.
Previous efforts for disposing waste textile and home furnishing fiber materials by individuals and corporations have relied on: burning the waste fibrous materials in massive incinerators; separating the yarn by their density followed by depolymerization to recover the monomers of the polyamides or polyester material; using the fibers in special products such as cotton in paper making; using supercritical fluids to dissolve the fibers followed by precipitation; and melt extruding the unseparated carpet components into a polyblend composite. The above processes have not been satisfactory from either environmental or economic factors, while the melt extruded polyblend has particularly weak interfacial adhesion between the incompatible blend components and does not produce a very satisfactory product.
The above shortcomings are overcome by the technology described in the instant invention. Through the use of a structural adhesive which coats unsegregated carpet fibers and/or blends of unsegregated carpet fibers with fabric fibers, followed with subsequent curing of the structural adhesive through the application of heat and pressure, a fiber-filled composite is produced which has applicability as a replacement for natural wood products, thereby conserving another natural resource.